The present invention relates to a class of ionene polymeric compounds which are useful as antimicrobials in pharmaceutical and cosmetic compositions. In particular, the present invention relates to certain polyethylene oxide (PEO)-containing polymeric quaternary ammonium compounds. These compounds are useful as disinfectants and preservatives for pharmaceutical products, including ophthalmic compositions and contact lens care products.
It is well known that small organic compounds, such as benzalkonium chloride (BAC), chlorhexidine, thimerosal have excellent antimicrobial activity. These compounds have been commercially used as preservatives and disinfectants for many years; however, there are some significant disadvantages to using these compounds, especially in ophthalmic and contact lens compositions. In particular, it is now known that these small organic antimicrobials are often toxic to the sensitive tissues of the eye and can accumulate in contact lenses, particularly soft, hydrophilic contact lenses. Accumulation of these antimicrobial compounds in contact lenses may cause eye irritation, and leaching of such compounds may occur while the lens is in the eye, causing further irritation and possibly damaging the cornea.
Several classes of polymeric antimicrobials were subsequently developed to overcome the disadvantages of the above-described monomeric compounds. These polymeric antimicrobials had lower cytotoxicity and had minimal interaction with biomaterials. Such antimicrobials include those described in U.S. Pat. Nos. 3,931,319; 4,001,432; 4,012,446; and 4,836,986.
U.S. Pat. No. 5,277,901 discloses certain antimicrobial PEO-containing quaternary ammonium polymers as useful for ophthalmic compositions, such as contact lens cam compositions, when combined with at least one other antimicrobial agent. The additional antimicrobial agent is preferably an urea component.